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Yandex Cloud Functions

Python function call handler

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A call handler is a method used to process each Python function call. When creating a function version, you should specify an entry point that consists of a file name and a call handler name (such as, main.handler).

Note

At any given time, a single function instance processes only one request. This allows you to use global variables without having to provide data integrity control.

When invoking the handler, the runtime provides the following arguments:

  1. Request body (event parameter):

    • If the request body is a JSON document, it will be converted to dict using the json.loads method.
    • If a function was invoked with the ?integration=raw request string parameter, the HTTP request body is provided to the function as is (unprocessed).

  2. Invocation context (context parameter).

    The context contains the necessary information about the function version. The structure of this object is described in Python function invocation context.

Handler types

A function can use both synchronous and asynchronous request handlers.

Synchronous handler

To have the output returned, use the return statement or raise an exception using the raise statement. A synchronous function must return a result or throw an exception.

Asynchronous handler

A handler can be an async def asynchronous function. In this case you can use the following statements:

  • return: Returns the function response.
  • raise: Reports an error to the runtime environment.
  • await: Tracks the execution of asynchronous function invocations.

Note

The service only supports the asyncio library as a runtime environment for asynchronous functions.

For more information about development using async/await, see the relevant documentation section.

Examples

HTTP request structure output

The following function outputs the request structure and invocation context to both the execution log and function response:

import json


def handler(event, context):
    return {
        'statusCode': 200,
        'body': json.dumps(
            {
                'event': event,
                'context': context,
            },
            default=vars,
        ),
    }

Function invocation example:

curl --data '{"hello": "world"}' -H 'Content-Type: application/json' https://functions.yandexcloud.net/d4eo2faf62**********?param=one

Result:

{
    "context": {
        "aws_request_id": "6e8356f9-489b-4c7b-8ba6-c8cd74f25455",
        "deadline_ms": 1657713543198,
        "function_name": "d4eo2faf62**********",
        "function_version": "d4e3vrugh3**********",
        "invoked_function_arn": "d4eo2faf62**********",
        "log_group_name": "ckgjmanjlh**********",
        "log_stream_name": "d4e3vrugh3**********",
        "memory_limit_in_mb": 128,
        "request_id": "6e8356f9-489b-4c7b-8ba6-c8cd74f25455",
        "token": {
            "access_token": "<IAM token>",
            "expires_in": 42299,
            "token_type": "Bearer"
        }
    },
    "event": {
        "body": "{\"hello\": \"world\"}",
        "headers": {
            "Accept": "*/*",
            "Content-Length": "18",
            "Content-Type": "application/json",
            "Host": "functions.yandexcloud.net",
            "User-Agent": "curl/7.64.1",
            "X-Forwarded-For": "109.252.148.209",
            "X-Real-Remote-Address": "[109.252.148.209]:2816",
            "X-Request-Id": "6e8356f9-489b-4c7b-8ba6-c8cd74f25455",
            "X-Trace-Id": "e9fe9b05-c1aa-4fb8-94d8-a514fd6f3ff7"
        },
        "httpMethod": "POST",
        "isBase64Encoded": false,
        "multiValueHeaders": {
            "Accept": [
                "*/*"
            ],
            "Content-Length": [
                "18"
            ],
            "Content-Type": [
                "application/json"
            ],
            "Host": [
                "functions.yandexcloud.net"
            ],
            "User-Agent": [
                "curl/7.64.1"
            ],
            "X-Forwarded-For": [
                "109.252.148.209"
            ],
            "X-Real-Remote-Address": [
                "[109.252.148.209]:2816"
            ],
            "X-Request-Id": [
                "6e8356f9-489b-4c7b-8ba6-c8cd74f25455"
            ],
            "X-Trace-Id": [
                "e9fe9b05-c1aa-4fb8-94d8-a514fd6f3ff7"
            ]
        },
        "multiValueParams": {},
        "multiValueQueryStringParameters": {
            "param": [
                "one"
            ]
        },
        "params": {},
        "pathParams": {},
        "queryStringParameters": {
            "param": "one"
        },
        "requestContext": {
            "httpMethod": "POST",
            "identity": {
                "sourceIp": "109.252.148.209",
                "userAgent": "curl/7.64.1"
            },
            "requestId": "6e8356f9-489b-4c7b-8ba6-c8cd74f25455",
            "requestTime": "13/Jul/2022:11:58:59 +0000",
            "requestTimeEpoch": 1657713539
        },
        "url": ""
    }
}
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